1. Field of the Invention
The present invention relates to a liquid crystal display (“LCD”), and more particularly, to a liquid crystal display, which is driven by a field sequential color (“FSC”) method or a color sequential display (“CSD”) method.
2. Description of the Related Art
An LCD comprises an LCD panel comprising a thin film transistor (“TFT”) substrate on which TFTs are formed, a color filter substrate on which color filters are formed, and a liquid crystal layer interposed between both substrates.
Generally, a conventional LCD comprises a color filter layer composed of three colors such as red (“R”), green (“G”) and blue (“B”), and may also be primary colors. The color filter layer controls the transmittance of light passing through the color filter layer, thereby displaying a required color.
Recently, an LCD has been created using an FSC method. The FSC method illuminates independent R, G and B light sources sequentially and periodically, and transmits a color signal corresponding to each pixel with a synchronization with the lighting period, thereby producing a full color image. This FSC method has advantages of enhancing an aperture ratio and a yield since a pixel is not divided into subpixels and reducing the number of driving circuits, which is needed for each subpixel, by one-third.
In this FSC method, the three light sources are sequentially illuminated to form one frame. Therefore, the FSC method requires a frequency three times higher than that of the conventional driving method. With the FSC method, the term frequency means how many times the frames are refreshed in one second. As the display apparatuses become larger, the number of gate lines increases, yet a gate on time decreases. The gate on time represents how long a gate on voltage is applied to one gate line. Therefore, the gate on time is the reciprocal of the product of the frequency and the number of the gate lines. As the gate on time decreases, a data signal is not sufficiently applied to the pixel. This causes a charging rate within the pixel electrode to decrease and quality of the display apparatus to deteriorate. Further, the area of a pixel charged by one TFT increases since one pixel is not divided into three subpixels, thereby reducing the charging rate.
Accordingly, methods have been discussed including using low-resistance wire, increasing an area of the TFT or making a thickness of a gate insulating layer thinner in order to prevent reduction of the charging rate, yet a need for enhancement of the charging rate still remains.